Purpose is to study the process of learning compensatory speech patterns, when a dental appliance causes speech interference. Acoustical analysis of speech, and physiological measures of jaw motions, larynx position and vocal fold activity, and timing and location of tongue-palate contact will be made. Normal volunteers will wear experimental alveolar-palatal prostheses for a period of several weeks, and data on speech characteristics will be obtained before, during, and after speech adaptation. A follow-up recording will be made after a month to see if compensatory speech patterns that had been previously learned will be retained. BIBLIOGRAPHIC REFERENCES: Hamlet, S. and Stone, M. "Nature of Compensatory Speech Pattens: Mechanisms Responsible for Vowel Changes". Paper Presented at the 90th meeting of the Acoustical Society of America. Abstract: J. Acoust. Soc. Amer. Vol. 58 (Suppl. 1): S112 (1975).